275/55r20 vs 275/60r20 Tire: What’s the Difference?

The numbers 275/55r20 and 275/60r20 on the sidewall of the tire are two standard tire sizes. They represent measurement data regarding the ring-shaped rubber that wraps around the wheel rim of an automobile. 

Learning about this data, particularly when you decide to interchange or replace a tire, is essential because even minor changes in the measurement can significantly influence the wheel’s dimension and top speed.

In this post, we’ll examine 275/55r20 vs. 275/60r20 tires to see if they’re interchangeable.  You’ll also learn how to read tire sizes; keep reading to find out more!

275/55r20 vs. 275/60r20 Tire: Comparison Table

The table below shows how the 5% change in the aspect ratio between 275/55r20 and 275/60r20 Tire changes the other measurements.

275/55r20 TireType275/60r20 Tire
31.91 Inches or 810.5 mmDiameter difference 1.08 (27.5) 3.4% inches (mm)32.99 Inches or 838 mm
10.83 Inches or 275 mmWidth difference 0 (0) 0% inches (mm)10.83 Inches or 275 mm
100.25 Inches or 2546.26 mmCircumference difference 3.4 (86.39) 3.4% inches (mm)103.65 Inches or 2632.65 mm
5.95 Inches or 151.25 mmSidewall Height difference 0.54 (13.75) 9.1% inches (mm)6.5 Inches or 165 mm
632.04 RPM or 392.73 KMRevolutions per mile difference -20.74 (-12.89) -3.3% (km)611.3  RPM or 379.84 KM

According to this table, as you can see, the width remains the same for both the tire sizes 275/55r20 and 275/60r20, which supports the interchangeability of tires.

However, there is a big jump in the sidewall height. The height of the Tire 275/60r20 has increased by 9.1%. Such changes in size do not support the interchangeability of tires. 

On the other hand, there is also a 3.4% jump in the diameter and circumference. Generally, it is recommended that you should not switch tires if the percentage change in diameter is more than 3%. 

Well, If you want to replace the current tire size  275/55r20 with the latest 275/60r20 Tire, you might face issues. It is clear from the table that the tire 275/60r20 will have more diameter, circumference, and sidewall height.

Since the changes are more than 3%, staying with your current tire size is better.

How to read the tire sizes 275/55r20 and 275/60r20?

There are four parts to the tire size 275/55r20, and each part bears a certain meaning. Before you decide to interchange or replace the Tire, you must learn about them. Here is the explanation of each part of the tire size 275/55r20.

  • 275 indicates the width of the tires in millimeters
  • 55 indicates the percentage of height in relation to the width or the Aspect Ratio
  • R indicates Radial Construction
  • 20 indicates the Diameter of the Rim

Doing the Same for Tire Sizes 275/60r20

  • 275 indicates the width of the tires in millimeters
  • 60 indicates the percentage of height in relation to the width or the Aspect Ratio
  • R indicates Radial Construction
  • 20 indicates the Diameter of the Rim

What’s The Difference Between 275/55r20 and 275/60r20 Tire?

By now you’ve learned the basics of using two tires interchangeably, now let’s see the theory implemented in a real example. Below, we have compared 275/55r20 and 275/60r20 tires in terms of width, aspect ratio, construction materials, and rim diameter. 

Width

If you measure from one sidewall to the other sidewall of a tire, you will get the width. It is expressed in millimeters. 

You can instantly learn the Width of a tire just by looking at the tire size index.

The first three digits of a tire size index indicate the Width of that tire. As you can see, the first three digits of 275/55r20 are 275. It means the width of that tire is 275 millimeters. 

Likewise, the three-digit number of 275/60r20 is 275. It means the Width of that tire is 275 millimeters. So the difference in the Width is 275 – 275 = 0 millimeters.

Now, if you switch to the tire size which is 0 millimeters more or less in Width, it shouldn’t be a problem. 

But you cannot switch tire size depending on Width only. You must consider the Sidewall Height as well. The Sidewall Height depends on Width and Aspect Ratio.

Aspect Ratio

As you can see, the only difference between the two Tire sizes is the aspect ratio. The aspect ratio of 275/55r20 is 55, whereas the aspect ratio of 275/60r20 is 60. On the other hand, the width and the Rim Diameter of the two Tire sizes are identical.

So to check the interchangeability of these tires, our sole concern is to analyze how the differences in the aspect ratio impact the other measurements. Let’s start with the simple question first: what is the aspect ratio? And its relation with other measurements.

Aspect Ratio is the ratio of the sidewall from wheel to tread and the width. This measurement is usually represented in a percentage.

Equation: Height of a Sidewall = Aspect Ratio of Tire x Width

In our example, 275/55r20 Tire size has a width of 275 with an aspect ratio of 55%. So the sidewall height will be 275 x 0.55 or 6.0 inches or 151.25 mm. You can get the number by simply putting the value on the equation.

The Aspect Ratio of Tire 275/60r20 is 5% more than Tire 275/55r20. This increase changes the value of the sidewall height, diameter, circumference, and a total number of revolutions per mile.

Construction Type

The tire size index informs you about the Construction Type of a tire. It is expressed by a letter in the tire size index. 

Both 275/55r20 and 275/60r20 have the same letter ‘R’. So, both the tires have Radial Construction in terms of construction type.

Such tires have a sophisticated construction with square footprints on the top. The Radial tires are ideal for driving on-road. 

They are resistant to heat and water. They are next-gen tires and can provide great fuel efficiency.  

Another famous construction type is Bias Ply. They are also known as Cross-ply. It is expressed by the letter ‘B’ in a tire size index. This type is great for driving off-road.

Rim Diameter

To know which tire size fits your vehicle, you must know the wheel rim size of your vehicle as well as the Rim Diameter of a tire.

For instance, if your vehicle has a 16-inch wheel rim, you can use the tire which has a 16-inch Rim Diameter.

By looking at a tire size index, you can learn instantly the Rim Diameter of a tire. The last two digits of a tire size index indicate the Rim Diameter. It is measured in inches. 

As you can see, the Rim Diameter of 275/55r20 is 20 inches. Similarly, the Rim Diameter of 275/60r20 is 20 inches.

It means that if your vehicle has a 20-inch wheel rim, you can use both tire sizes. But make sure to use the same size tires for all the wheels.

Can you interchange Between 275/55r20 and 275/60r20 Tire?

From the relative changes in the measurements, it is clear that replacing tire  275/55r20 with 275/60r20 might not be a good idea.

A Good Rule of Thumb: Always aim to keep the replacement tire and wheel combination within 3% of your existing tire. If you still decide to switch, keep in mind the potential issues, including rolling resistance, changes in the speedometer, and fuel economy.

Speedometer Difference: Using the current Tire Size 275/55r20 Instead Of the New Tire Size 275/60r20

Look at the Table. It shows differences in speedometer reading and the actual speed at any given time when the current Tire Size is 275/55r20 Instead Of 275/60r20. 

Speedo ReadingActual Speed
20 mph (32.19 km/h)20.68 mph (33.28 km/h)
25 mph (40.23 km/h)25.85 mph (41.6 km/h)
30 mph (48.28 km/h)31.02 mph (49.92 km/h)
35 mph (56.33 km/h)36.19 mph (58.24 km/h)
40 mph (64.37 km/h)41.36 mph (66.56 km/h)
45 mph (72.42 km/h)46.53 mph (74.88 km/h)

Speedometer Difference: Using current Tire Size 275/60r20 Instead Of New Tire Size 275/55r20

The table shows the differences in speedometer reading and the actual speed at any given time when the current Tire Size is 275/60r20 Instead Of 275/55r20.

Speedo ReadingActual Speed
20 mph (32.19 km/h)19.34 mph (31.13 km/h)
25 mph (40.23 km/h)24.18 mph (38.91 km/h)
30 mph (48.28 km/h)29.02 mph (46.7 km/h)
35 mph (56.33 km/h)33.85 mph (54.48 km/h)
40 mph (64.37 km/h)38.69 mph (62.26 km/h)
45 mph (72.42 km/h)43.52 mph (70.04 km/h)

What you must consider Before Interchange or Replace Tire? 

There are important things to consider Before replacing or swiping the Tires. You cannot simply replace the 275/55r20 tire with the 275/60r20 tire that is in a different shape.

For Example, if the aspect ratio of the existing tire is 40%, replacing it with a tire that has an aspect ratio of  45% might not be a good option.

Doing so will have a variety of consequences on the car’s overall performance, such as variations in top speed and speedometer.

However, to a certain extent, such as minor changes in the diameter or the sidewall, you can switch Tires. However, this can only be done in compliance with the manufacturers’ recommendations.

Anyway, When replacing the Tire, the simple guideline to follow is that the current tire’s size, load index, and speed rating should all match with the replacement Tire.

Load Index and Speed Index of a Tire 275/55r20 and 275/60r20

The load index refers to the maximum load-bearing capacity, whereas the speed index refers to the Tire’s maximum allowable speed at a full load. These are very crucial stats to know before you decide to interchange tires.

Index information can be found on the sidewall right after the Tire size number. It is a combination of numbers and letters that bear a particular meaning. 

Check The load and speed index. They must be as close as possible to fit precisely. These values change depending on the vehicle’s weight and wheel size. Here is a table that shows various load and speed indexes, so you get the idea.

Load IndexKgSpeed IndexSpeed Limit
65290QUp to 160 Km/h
66300RUp to 170 Km/h
67307SUp to 180 Km/h
68315TUp to 190 Km/h
69325HUp to 210 Km/h

Size of the Tire 

The size of the Tire is another vital piece of information to know to exchange the tires properly. The large number on the sidewall shows the tire size.

For Example, the marking 275/55r20 on the sidewall represents the size of the Tire. You can also find it in the user manual, on the sidewall, and in other places such as inside the fuel flap or glove compartment.

What Size Tires Is 275/55r20 in Inches?

275/55r20 tires have a 31.9″ diameter, 10.8″ section width, and 20″ wheel diameter.

The circumference is 100.2″, and they make 632 revolutions per mile. The Sidewall Height of this Tire is 6.0 inches.

What Size Tires Is 275/60r20 in Inches?

275/60r20 tires have a diameter of 33.0″, a section width of 10.8″, and a wheel diameter of 20″.

The circumference is 103.6,” and they have 612 revolutions per mile. The Sidewall Height of this Tire is 6.5 inches.

Conclusion

So, you have learned how even the 5% change in the aspect ratio influences the other measurements and dramatically influences your decision on interchangeability.

While interchanging tires, make sure to keep the variable of the replacement tire as close as possible to the current tire. Also, calculate the potential consequences before swiping.

Next time around, it will be easy for you to break down the car-size numbers and decide which tires are perfect for your car. 

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